In the resignation letter sent to MQM-P Convenor Khalid Maqbool Siddiqui, which was also posted on Twitter, Abidi wrote: "This is to bring to your attention that I will not be able to continue participation with MQM Pakistan due to personal reasons."

"Therefore, it is requested to accept my resignation from basic membership," he added.

Sources said that the former member of the National Assembly (MNA) has quit in disappointment over the party overlooking him and nominating Faisal Sabzwari in his stead.

This is a major setback for the MQM-P, especially considering that the resignation comes ahead of the by-polls, wherein Abidi believed he would be nominated in the NA-243 constituency.

It is noteworthy that Prime Minister Imran Khan had won during the July 25 general election but later let go of the NA-243 seat.